import java.text.DecimalFormat;
import java.util.Scanner;
public class pp36
{
   public static void main (String[] args)
   { 
      double a,b,c,s,area,d;
      Scanner scan = new Scanner (System.in);
      DecimalFormat fmt = new DecimalFormat ("0.###");
  
      System.out.println ("Enter the length: ");
      a = scan.nextDouble();
      System.out.println ("Enter the length: ");
      b = scan.nextDouble();
      System.out.println ("Enter the length: ");
      c = scan.nextDouble();
      s = (a + b +c) / 2;
      d = s * ((s - a) * (s - b) * (s - c));
      area = Math.sqrt(d);
      System.out.println ("The area: " +fmt.format (area));
   }
}
